Manufacture of resilient pads



April 18, 19 3- c. FIELD El AL MANUFACTURE OF RESILIENT PADS Filed June 12, 1929 my m Crosby BIbli0n1.62zn 0bell ATTOR N E Y I Patented A pr. 18, 1933 UNITED; STATES PATENT OFFICE CROSBY FIELD, OI BROOKLYN, AND CLINTON L. CAMPBELL, OF SCABSDALE, NEW YORK, ASSIGNOBS 1'0 BBILLO IANUFACTURING CO'MPANY, INC., A. CORPORATION F NEW YORK mumc'ruan or swim PADS The present invention is concerned withresilient pads which' though preferably stant resilience under long repeated compresare especiall sions is necessary for commercial success, but adapted for embodiment in laundry or c othes press pads to supplement or replace the conventional spring cushlon's and other fibrous materials which are now commonly-employed on the press bucks.

Objects of the invention are to provide a pad of this type which will be of umform and endurin resiliency when subjected to often repeate relativelyhigh compressions; which will not develo rust in storage, and which when in use will efl'eotively safeguard against breaking the most delicate buttons or injuring the finest fabrics WhlCh may be ironed by the press. 7

The resilient quality of steel wool 1s well known but no one has thus far succeeded in controlling this quality so as to make the pads sufiiciently standardized and endurlng for the particular purpose with which the present invention concerns itself. Our 1n- .vention is based on the discovery that this is because no prior pads, whether for abrasive or for cushioning purposes, have been given initial compression substantially greater than the pressures which they are sub ected to in use, and in most of them, the initial comof use, sometimes only a few months and sometimes only a fewweeks, the thiclmess of the'pad has been reduced to that of a mere sheet, and the range of resilience is so reduced as to render the pad inoperative for purposes above described, such as avoiding uttons or injury of fine fabrics. We have further discovered tha't the steel wool ads or mats can be rendered uniformly an enduringly resilient throughout a desired range of sprmg movement, and that this may be accomplished by making the initial pad of relatively great thickness and subjecting it to an initial pressure that is relatively enormous as compared with the ordinary pressures or stresses to which it is subjected in use. Thus,

the initial set ofthe fibers of the pad so far exceeds that producible by use pressures, that the adbecomes dependable as to constant thic ness and range of resilience.

We utilize this discovery by producing a pad or mat of wool which has been subjected to a comparatively high pressure in a forming die, the pressure being suflicient to impart to the steel wool mass a definite and substantially permanent contour. These pressures are in general far greater than is ever applied tosteel wool scouring pads used for abrasive purposes and, in fact, are such as to render the fibers extremely stiff and far too brittle and too easily broken by pressures edgewise to the initial set, such as are always applied in ordinary use of scouring pads. Tests with these unprecedented pressures have demonstrated that there are limits of high forming pressure which must not be exceeded, for otherwise the mass will be permanently reduced to undesirable stiifness and hardness, flatwise as well as edgewise, and will not have a range of spring action such as is required for a spring cushion pad. In this connection it mayv be noted thatthe very delicate and relatively minute steel wool fibers, when bundled or bunched into a matted mass of interlaced intercurled fibrous material, will produce a mat having an astonishingly'high elastic range and capable of withstanding compression in the order of a third of a ton or more per square inch without destruction of its resiliency.

In practice when forming a pad we spread the desired quantity of steel wool of fairly the proper size and shag and subject the mass to a compression w ch flattens it out into almost sheet like form. The mass has little tendency to lateral expansion even if laterally unrestrained. When the pressure is relieved the pad quickly springs back to a substantial t iclmess which forthe preferred sizes of fiber and thickness of. pad will not exceed three times the initial compression thickness of the sheet, so that in its expanded condition the resulting spring pad is of very substantial density.

If this pad is held in place on a press buck by the usual inner covering of flannel and tautly stretched outer covering of cotton fabric it will have no tendency to further exand in thickness and will as above suggested he of uniform resiliency in all directions under all ordinary pressures to which it may be subjected in the press, these pressures during use being commonly quite low as compared to the forming pressure initiall applied on the pad, say about seven poun s per square inch.

In cases where the pads are to be stored for comparatively long periods of time before application to -a press buck they will have a tendency to gradually increase in thlckness. This tendency we overcome by packaging the pads in a shallow box which is of slightly less depth than the normal thickness of the pads and which holds the pads under slight com ression during storage.

The pads, when on the press, are subjected -to the usual high press temperatures which reclude the presence of moisture,'and are urthermore enclosedby the flannel which substantially excludes air so that they have little or no tendency to oxidize or rust. During stora e, however, and during'manufacture the ormation of rust or incipient rust must be arded against. This we preferably accomplish by cutting the wool in the presence of a compound which completely coats it with a very thin paraifin film. Ordinary methods of cutting with oil are avoided to prevent the mass from developing undue easiness under subsequent compression.

ry cutting methods are not satisfactory because they slow down the cutting process and wear out the cutting knives and do not prevent rust during storage.

When the pads are put in use the intense heat of the press quickly burns out some of the .constituent elements of the paraffin which as' above explained has primarily the function of preventing the formation of incipient rust during manufacture and storage of the pads, the residue of-the parafiin forming a permanent black protective coating on the individual fibers of the steel wool, so that there is little or no tendency for them to rust in use.

The invention may be more fully under-.-

nection with the accompanying drawing,

wherein Fig. 1 is a sectional view showing one of the pads in place on a press buck; Fig. 2 is a perspective view of the pad; Fig. 3 is a transverse sectional view therethrough;

Fig. 4 is a diagrammatic sectional view of the forming press; and

' Fig. 5 is a sectional view of the ackage.

The finished pad 10 as seen in igs. 2 and 3 is about five-eighths of an inch thick and is held in place on the press buck 11 by the conventional inner layer of flannel 12 and the outer layer 13 of light cotton fabric.

An important feature of a steel wool pad formed in accordance with the present invention is that, .due to its ready flexibility it may, if oversized, be folded around the edges of the press buck. A

The means for holding these fabric layers tautly stretched so as not to wrinkle the goods 276,317, for conveyor and storage apparatus for metal wool machines, filed 'August 3rd, 1928. v The invention described therein indicates a method of obtaining the wool in a loose fibrous tangled mass of rather flufly constituency. We do not, of course, limit our invention to wool made in this fashion, but such wool has been found preferable.

About three pounds of this fluif is gathered up, slight y compacted by hand and spread evenly in the female element 14 of the forming die mounted for instance on the Plunger of ahydraulic ress. In a articuar case the three poun s, of wool led the female dieto a depth of about six inches. Wool filled element 14 is then moved upwardly by the lunger into coaction with the male element 5 of the die and the material sub-- jected to a pressure in the order of one hundred tons for a spring pad of about 300 square inches area or about 650 to 700 pounds per square inch which flattens the mass out into a very thin sheet, no clearance in fact being provided between the working faces of the members 14 and 15. When the pressure is relieved the flattened mat quickly expands to a thickness two to four times the minlmum thickness under the formin pressure, dependent on the sizeof the g ers, and in a given case, the expanded thickness may be about five-eighths ofan inch at which time its density is around 0.0135 pounds per cubic inch. It will be noted that in the above illus- 65 stood from the following description in contrativecase where the forming pressure of the pad is, say, 600 to 700 pounds per square inch, said pressure is approximately 100 times ordinary pressure applied by the buck in a laundry or clothes pressing machine. While this is by no means the lower limit of forming pressure that will give a useful density, it is to be noted that in all cases my invention requires that the initial forming pressure be vastly greater than the use pressures so that the pad will stand up under continued use pressure for long periods of time, that is, a year or years, as contrasted with a limit of a ver few weeks or months, characteristic of steel not been given such initial forming pressure.

We have thus far been unable to find accurate limits for the effective compression range and density ran e although we have discovered that exceedingly high pressures, say around 850 tons or, say, 5,000 pounds per square inch, flatten and apparently weld the individual fibers of the mass together, completely killing all resiliency; also that ressures of less than fifty tons or 333 poun per square inch do not give the desired set or more or less permanent form desired.

The pressures are subject to change in any event where larger charges of wool are used for a given area of die or where wool of other grades is used.

To prevent further expansion of the mat during storage and shipment we package them under slight compression in shallow boxes 20 of fiber board or corrugated paper board closed by the usual taped paper strlps 21.

The pads embodying the invention and produced by our method may" have various uses other than the specific one discussed herein. They are particularly suited for instance for use as floor mats under rugs and carpets.

With provisions such as those described above we have found that coarse wool commonly known as No. 3 grade gives the best results, although finer grade. material might be used when the pressures of manufacture are not so high.

When used for laundry or clothes press purposes, the mats may either entirely replace the usual spring pads or may serve to supplement them. When used on presses which pass live steam through the fabric being pressed, it will be obvious that the wool should be effectively permanently rustproofed.

We claim:

1. A method of making resilient pads of metal wool which includes subjecting a loose matted mass of wool informing dies to a pressure in excess of one sixth of a ton per square inch, the quantit of wool being such that the wool is flattene out into a thin sheet under the dies and expands to a thickness of wool pads which have about three-quarters of an inch when the pressure is relieved.

2. As a new article of manufacture, a flat spring cushion pad of resilient wool having its fibers initially crushed down and set to a density approximating .01 pound or more per cubic inch.

3. A spring cushion for exposure to heat and steam, consisting of a pad or mat of dense but resilient metal wool, the individual fibers of the steel wool being coated with paraflin and having been set by compression substantially greater than 300 lbs. per square inch and substantially less than 5,000 lbs. per square inch.

Signed at Brooklyn, in the county of Kings and State of New York, this 10 day of June,

CROSBY FIELD. CLINTON L. CAMPBELL. 

